As the size of the electronic devices is reduced, new materials with a low dielectric constant (k), such as materials with dielectric value as low as 2.2, are used in forming the electronic devices.
Plasma-deposited porous low k films are one class of materials that is able to satisfy such a requirement. The presence of pores and carbon, which contributes to low dielectric value, creates significant process integration challenges since the pores are susceptible to etching, ashing, and plasma damages. Therefore, a k-restoration process is usually needed to restore the porous low-k films after formation and/or after integration.
Traditionally, two different chambers are needed for k-restoration. One chamber for chemical treatment of the low-k films, such as silylation, or deposition of a thin film for surface treatment of the low-k films. A different chamber is used for pore sealing using UV (ultra violet) curing. Traditional k-restoration is performed in separate chambers because the chemical surface treatment uses a showerhead to supply a processing gas including halogen or ozone while the UV chamber uses a quartz window which usually is not compatible with halogen and ozone. However, the two chamber k-restoration process increases cost of ownership by requiring two chambers and additional time for substrate transfer.
Therefore, there is a need for an improved apparatus and method for k-restoration processes.